The International Organization for Migration (IOM) says 25 Ethiopian refugees have gone missing after being forced into the sea as they approached the coast of Yemen.

The men were on one of the four boats that ferried Ethiopians to Yemen on Thursday, Mohammed Abdiker, director of operations and emergencies at the UN migration agency, tweeted on Friday.

Abdiker further said that the people on the boat were dumped into the sea and “forced to swim to shore” as they approached Yemen's Shabwa province from Somalia.

No bodies have been recovered.

IOM spokesman Joel Millman said nearly 600 Ethiopian refugees, men and women, were aboard the ships. The figure is an unusually large number of refugees to arrive off the Yemeni province at one time.

According to International Organization for Migration figures, some 87,000 people risked their lives trying to reach Yemen from the Horn of Africa by boat in 2017.

At least 30 African refugees drowned when their boat capsized off the coast of war-torn Yemen last month with reports that their smugglers opened fire on those on board.

Saudi Arabia and its allies launched a bloody military campaign early in 2015 and have, ever since, been ceaselessly pounding the country in an attempt to reinstall Abd Rabbuh Mansur Hadi, Yemen’s former president and a staunch ally of Riyadh, and to crush the Houthi Ansarullah movement. The Saudi-led coalition has also maintained an embargo on the country where, so far, at least 13,600 civilians have been reportedly killed.

Yemen’s lawless southern regions, which are mostly controlled by militants loyal to Saudi Arabia and Yemen’s resigned president Abd Rabbuh Mansur Hadi, have become a fertile ground for smugglers who vow to transfer refugees from the region to wealthier Arab states in the Persian Gulf.

However, most of those smugglers leave refugees at sea as they fear being arrested by militants or Saudi Arabia’s military forces.